The present invention relates to respirators or face masks which are capable of being folded flat during storage and forming a cup-shaped air chamber over the mouth and nose of a wearer during use.
Filtration respirators or face masks are used in a wide variety of applications when it is desired to protect a human""s respiratory system from particles suspended in the air or from unpleasant or noxious gases. Generally such respirators or face masks are of one of two typesxe2x80x94a molded cup-shaped form or a flat-folded form. The flat-folded form has advantages in that it can be carried in a wearer""s pocket until needed and re-folded flat to keep the inside clean between wearings.
The flat-folded form of face mask has been constructed as a fabric which is rectangular in form and has pleats running generally parallel to the mouth of the wearer. Such constructions may have a stiffening element to hold the face mask away from contact with the wearer""s face. Stiffening has also been provided by fusing a pleat across the width of the face mask in a laminated structure or by providing a seam across the width of the face mask.
Also disclosed is a pleated respirator which is centrally folded in the horizontal direction to form upper and lower opposed faces. The respirator has at least one horizontal pleat essentially central to the opposed faces to foreshorten the filter medium in the vertical dimension and at least one additional horizontal pleat in each of these opposed faces. The central pleat is shorter in the horizontal dimension relative to the pleats in the opposed faces which are shorter in the horizontal dimension relative to the maximum horizontal dimension of the filter medium. The central pleat together with the pleats in opposed faces form a self-supporting pocket.
Also disclosed is a respirator made from a pocket of flexible filtering sheet material having a generally tapering shape with an open edge at the larger end of the pocket and a closed end at the smaller end of the pocket. The closed end of the pocket is formed with fold lines defining a generally quadrilateral surface comprising triangular surfaces which are folded to extend inwardly of the pocket, the triangular surfaces facing each other and being in use, relatively inclined to each other.
More complex configurations which have been disclosed include a cup-shaped filtering facepiece made from a pocket of filtering sheet material having opposed side walls, a generally tapering shape with an open end at the larger end and a closed end at the smaller end. The edge of the pocket at the closed end is outwardly bowed, e.g. defined by intersecting straight lines and/or curved lines, and the closed end is provided with fold lines defining a surface which is folded inwardly of the closed end of the pocket to define a generally conical inwardly extending recess for rigidifying the pocket against collapse against the face of the wearer on inhalation.
Further disclosed is face mask having an upper part and a lower part with a generally central part therebetween. The central part of the body portion is folded backwardly about a vertical crease or fold line which substantially divides it in half. This fold or crease line, when the mask is worn, is more or less aligned with an imaginary vertical line passing through the center of the forehead, the nose and the center of the mouth. The upper part of the body portion extends upwardly at an angle from the upper edge of the central part so that its upper edge contacts the bridge of the nose and the cheekbone area of the face. The lower part of the body portion extends downwardly and in the direction of the throat form the lower edge of the center part so as to provide coverage underneath the chin of the wearer. The mask overlies, but does not directly contact, the lips and mouth of the wearer.
The present invention provides a personal respiratory protection device comprising
a flat central portion having first and second edges,
a flat first member joined to the first edge of the central portion through either a fold-line, seam, weld or bond, said fold, bond, weld or seam of said first member being substantially coextensive with said first edge of said central portion, and p1 a flat second member joined to the second edge of the central portion through either a fold-line, seam, weld or bond, said fold, bond, weld or seam of said second member being substantially coextensive with said second edge of said central portion,
at least one of the central portion and first and second members being formed from filter media, and
said device being capable of being folded flat for storage with said first and second members being in at least partial face-to-face contact with a common surface of said central portion and, during use, being capable of forming a cup-shaped air chamber over the nose and mouth of the wearer with the unjoined edges of the central portion and first and second members adapted to contact and be secured to the nose, cheeks and chin of the wearer and the outer boundary of the unjoined edges which are adapted to contact the nose, cheeks and chin of the wearer being less than the perimeter of the device in the flat folded storage state. Additional portions may be optionally attached to the unjoined edges of the first and second members. Additional portions may be optionally attached to the central portion.
The configuration of the flat-folded respiratory device may be rectangular to substantially elliptical. The respiratory device, when unfolded for use, is substantially cup-shaped. The filter media which comprises at least one of the first member, central portion and second member may be a nonwoven fabric such as one formed from microfibers or may be of several layers, each layer having similar or dissimilar filtering properties. The filter media may, of course, also comprise any two or all of the first member, central portion and second member as well as the additional portions.
The respiratory devices of the present invention may further comprise headbands or other means such as adhesive for holding the respiratory device in place on the face of the wearer, nose clips or any other means to provide good contact of the respiratory device with the nose of the wearer, exhalation valves, and other accouterments common to respirators and facemasks such as, for example, face seals, eye shields and neck coverings. When the respiratory device is constructed with a nose clip, the nose clip may be on the outer portion of the first member of the respiratory device and a cushioning member such as a piece of foam can be placed directly below the nose clip on the inner surface of the first member or the nose clip may be on the inner surface of the first member and a cushioning member can be placed covering the nose clip or when the respiratory device comprises multiple layers, the nose clip may be placed between layers.
The respiratory devices of the present invention include, for example, respirators, surgical masks, clean room masks, face shields, dust masks, breath warming masks, and a variety of other face coverings. The respiratory devices of the present invention can be designed to provide better sealing engagement with the wearer""s face than some other types of cup-shaped respirators or face masks which contact the wearer""s face at the periphery of the respirator at an acute angle with minimal contact region, thereby increasing discomfort to the wearer and potentially minimizing the engagement of the seal at the perimeter of the respirator.
Additionally provided is a process for producing personal respiratory devices to afford respiratory protection to a wearer comprising
a) forming a flat central portion, said central portion having at least a first edge and a second edge;
b) attaching a flat first member to said central portion at the first edge of said central portion with a fold, bond, weld or seam, said fold, bond, weld or seam edge of said first member being substantially coextensive with said first edge of said central portion;
c) attaching a flat second member to said central portion at the second edge of said central portion with a fold, bond, weld or seam, said fold, bond, weld or seam edge of said second member being substantially coextensive with said second edge of said central portion;
with the proviso that at least one of said central portion, first member and second member comprises filter media and said device being capable of being folded flat for storage and, during use, being capable of forming a cup-shaped air chamber over the nose and mouth of the wearer, and the unjoined edges of the central portion, first member and second member adapted to contact and be secured to the nose, cheeks and chin of the wearer and the outer boundary of the unjoined edges which are adapted to contact the nose, cheeks and chin of the wearer being less than the perimeter of the device in the flat folded storage state. Additional portions may be optionally attached to the unjoined edges of the first and second members.
Also provided is a process for producing personal respiratory protection devices comprising the steps of forming a rectangular sheet of filtering media, folding a first long edge toward the center of the sheet to form a first member, folding the second long edge toward the center of the sheet to form a second member and sealing the nonfolded edges. The process may optionally include additional portions attached to the first and second members at their unfolded edges through additional folds or bonds.
Further provided is a process for preparing personal respiratory protection devices comprising forming a first elliptical sheet of filter media having two edges, forming a second elliptical sheet of filter media having two edges, at least one side of each sheet having a common shape, bonding the common shaped edges, folding the unbonded edge of said second sheet toward the bonded edge, forming a third elliptical sheet of filter media having two edges, at least one edge of which has a common shape with the unbonded edge of said first sheet, placing said third sheet on said second sheet and bonding the common shaped edges of said first and third sheet.
Each process is amenable to high speed production methods and may comprise additional steps as needed for attachment of headbands, nose clips, and other typical respiratory device components.